Mastering the barbell row is one of the most important things a trainee can do in order to ensure proper upper back development. You can get wide from doing pullups and chins, but you can't get thick. You can get wide AND thick from doing rows. Great strength exercise as well, as you can develop your core musculature, which has carryover to the squat and deadlift

Generally, there are 3 styles of barbell rowing. Pendlay rows (also known as "JS Rows" and "Madcow Rows", however both Madcow and JS got the technique from Glenn Pendlay), the Yates row, popularized by the former Mr. Olympia, and the basic 45 degree row, which is what you usually see being performed by the majority of peeps in the gym.

"Yates row" - popularized by the previous Mr. Olympia, involves an upper body that is bent over at approximately 60 degrees above parallel, i.e. just basically a "forward lean".

It allows for a tremendous amount of weight, and it is a brutal upper/inner back workout. It also blows up the traps, but if you have weak lats, you will not get any further lat development. In other words, your traps will overpower your lats completely unless you have strong lats. This is NOT a "bring up your weak lats" type exercise. This is a "my lats kick ass, let's try something new to make them kick MORE ass" type of exercise.

Yates typically performed this with an underhand grip. He also tore a biceps as a result. I used this with great success, but I used an overhand grip as the underhand grip tore the hell out of my elbows. In both cases, a close grip is used, and you pull to the lower portion of the gut, underneath the navel.

Tips: NEVER straighten your elbows all the way at the bottom of the motion, but allow your shoulders and scapulae to stretch downward into a full stretch for the "start" position. Perform a shoulder shrug to begin the exercise and in a smooth motion follow up with a hard pull with the lats (i.e. yank elbows up and back) so the bar digs into your lower belly, and control the bar slowly back to the start position and full stretch. Try to pull your elbows back to keep the bar pinned to your lower gut. Also, use your lats to arch your upper back as well as maintaining that lower back arch throughout the motion.

Pendlay row - probably the exact *opposite* end of the spectrum as far as execution and body position. Maintaining a PERFECTLY PARALLEL upper body is the key. You will also use a relatively wide grip (I keep pinkies approximately 1/2" inside outer knurling on standard Olympic bar), and pull the bar into your lower ribcage/upper gut area. You must "deweight" between *every* repetition. That is, you actually put the bar down and release your grip so that you remove any type of static tension in the muscles at that time. Using the wider grip "reduces" the work the biceps has to do when you row so high on your body (lower ribcage vs. navel area)

Start off with the bar on the floor. Get your body into a parallel position initially. Keeping your upper body parallel, allow your shoulder blades to roll forward so that you can grip the bar as explained above. Without standing upright at all, explosively contract your shoulder blades together, and KEEP YOUR HIPS MOTIONLESS. There is *no* movement at the hips, i.e. do NOT stand up during this motion, you maintain the parallel upper body position throughout. Your lower back arches hard, your elbows pull outward and behind the body, but you do not stand up at all. Slam the bar into your upper gut/lower ribcage, then control the weight downward while maintaining the parallel upper body position. Use your lats to arch your upper back and pull your elbows "up" to pin the bar to your torso.

Tips: If you are able to row more than 135 with this exercise, use 35s so that you can get a better range of motion while pulling from more of a stretch position.
Use significantly less weight on this exercise than on Yates rows. It takes the traps out of the motion. For reference, I am able to use ALOT more weight on Yates rows than for Pendlay's for 5 "good" reps, a good 25-35% reduction in weight will probably be necessary.
Check my stupid picture for additional "visual" reinforcement of body position with Pendlay's.

basic "vanilla" bent row - involves a motion and body position about halfway between the 2 extremes mentioned above. Body position somewhere between 30 and 45 degrees, whichever is comfortable. hand position can be anywhere you feel you want to work. Your elbow flexors, rear delts, and traps can all assist pretty powerfully in this exercise, so it is easy to "lose" the motion by trying to use an excessive amount of weight. This will give you great rear delts and traps, but not much lat development. You have to really force the lats to work in this exercise.
Wide and close grips both work the lats hard, assuming proper execution and the ability of the trainee to force the lats to be the prime movers.
Generally, the wider your grip, the higher along your body you will want to pull. If you use a wide grip, pull to your upper gut/lower ribcage. If you use a closer grip, pull to your lower belly beneath your navel.

A lot is spoken about the "deweighting" portion of the row. Deweighting between reps is a tool in your toolbox. Use it as needed. In other words, you can get a great workout from doing "Pendlay rows without the deweighting". You stand on a platform and perform the row, but you allow tension to remain by keeping the bar in your hands and simply allowing your shoulder blades to roll forward, rather than releasing the bar on the floor. You do not HAVE to do the deweighting. You are selling yourself short, however, if you don't deweight at least some of the time. Consider Pendlay rows and "non-deweighted" Pendlay rows as 2 different exercises, really.

That goes for ALL of the rows. Take these as completely different exercises. Doing "barbell rows" can mean 1 of 4 (or more) exercises, as far as I'm concerned, because each of the above-described variations of the row are very different in form and function.

I troops,
I have to say I simply love the barbell bent over row. I have has a passion for that great movement for over 20 years myself. I started out rowing on top of a bench. Where I would row the bar up to my waist and go heavy.
But, just like evolution my ideas evolved.
I went to having the bar sit on a low squat rack or power rack like Dorian Yates. I then step foward and grab th bar with a palm to the rear thumbless grip. I then step back a pace bend foward a little deeper then Dorain and row the bar so that it hits my weight belt. I always strive for at least 5 plus reps.
ALthough I love to pull heavy. every time I step back and lean down my mind is hell bent on keeping my stance nice and low. Its hard but I know that if I keep low my lats and traps will grow. I call it the grow zone.
Gear - I love wrestling shoes, a thick single prong power lifting belt, neoprene shorts to keep the ole package tight, a good pair of cotton straps, a healthy dash of chalk on the hands and a go getten attitude.
I look at my bent rows just as serious as others do their dead lifts. I always do them first in my back routine.
So, If you love to train old style get in the grow zone.